Lubricating oil and method of lubricating



atented Mar. H, 1947 LUBRICATING H4 AND IWETHOD OF LUBRICATING Edwin C. Knowles, Frederic C. McCoy, and John A. Patterson, Beacon, N. Y., assignors, by mesne assignments, to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application May 2, 1941, Serial No. 391,468

4 Claims. (01. 258-45) This invention relates to improved lubricants adapted for service in internal combustion engines, and particularly to a lubricating oil containing small amounts of an additive ingredient capable of inhibiting or preventing the deterioration of the lubricating surfaces resulting from the corrosive action of the oil.

In the recent development of internal combustion engines, and particularly engines designed for heavy duty service, the trend toward high operating temperatures, high sustained speeds, reduction of clearances and hard bearing alloys, such as copper-lead, cadmium-silver, etc.. has necessitated an improvement in lubricants adapted for this service. These improvements even extend to the solvent-refined mineral lubricating oils of high viscosity index (V. I.) generally regarded as superior lubricants by conventional criteria. When operating under such severe conditions these mineral lubricating oils have the tendency to corrode or deteriorate the metal surfaces, especially the bearing surfaces, with which the lubricating oil comes in contact. To a great extent this may be overcome or reduced by the incorporation of additive components which possess anti-oxidant or anti-corrosive properties when dissolved or dispersed in mineral lubricating oils. By anti-oxidant or anti-corrosive properties is meant all those properties which effect a reduction or elimination of weight loss of the lubricated metal surfaces which result from the oxidizing or corrosive action of the mineral lubricating oils.

Many additive ingredients have heretofore been proposed or suggested for this purpose and particular attention has been given to the class of sulfurized compounds. Among the numerous sulfurized compounds suggested as corrosion inhibitors are the sulfurized terpene oils, such as pine oil, terpineol, turpentine, etc. In proposing this type .of sulfurized compounds considerable importance has been attached to the existence of such polar groups as hydroxyl and carboxyl groups within the compounds and their beneficial effect on the anti-oxidant or anti-corrosive action of the compounds when incorporated in lubricating oils.

The present invention is based upon the discovery of a novel class of oil-soluble or oilmiscible sulfurized terpene hydrocarbons containing no polar groups such as hydroxyl or carboxyl radicals within the molecule. It has been found that when small proportions of an oilsoluble sulfurized monocyclic terpene hydrocarbon are blended with a mineral lubricating oil adapted for use in internal combustion engines, a mineral oil composition is formed possessing exceptional anti-oxidant or anti-corrosive properties, together with improved load-carrying (E. P.) properties. Specifically, these compounds may be described as sulfurized derivatives of unsaturated monocyclic terpene hydrocarbons of the class of menthenes and menthadienes. Among the particular compounds found siutable for the purposes of the invention are the oil-soluble sulfurized derivatives of terpinolene; alpha, beta and gamma terpinene; limonene; dipentene; alpha and beta phellandrene; sylvestrene; carvestrene, menthene; carvo-menthene, and isomers thereof,

These sulfurized derivatives may be prepared by any of the accepted methods of sulfurizing unsaturated hydrocarbons, such as the direct combination with sulfur at atmospheric or superatmospheric pressure, or the reaction with sulfur under pressure of hydrogen sulfide as disclosed and claimed in the copending applications of Edwin C. Knowles and Frederic C. McCoy, Serial Nos. 358,876, 358,877, and 358,878, all filed September 28, 1940. These reactions are highly exothermic and yield sulfurization products of an unusually light color. The following examples are given as illustrating two of the methods which may be used:

EXAMPLE I grams of terpinolene and 45 grams of sulfur were mixed and charged in a 500 cc. stainless steel autoclave. The mixture was heated for one-half hour to 340 F. and maintained at IMO-360 F. for another half hour, with shaking every five minutes. The maximum pressure developed was 50 pounds per square inch. At the end of the reaction period the bomb was cooled and the reaction mixture vacuum steam-stripped to 300 F. at 15:55 millimeters mercury. 63 grams of the sulfurized product were then diluted with an equal volume of benzene and refluxed at -190 F., with violent agitation in the presence of a solution consisting of 126 grams of water, 63 grams of Na2S.9H2O, and 19 grams of sodium hydroxide, for a period of four hours. At the end of the treating period the mixture was allowed to cool and approximately 100 cc. of pentane were added, with shaking to facilitate separation. The bottom layer, which was dark orange red, was drawn off and the upper layer washed several times with water. This layer was then dried by filtration and the benzene and pentane evaporated on a steam bath, The resuiting sulfurized terpinoiene appeared as alight yellow-brown oil which analyzed 29.3% sulfur.

EXAMPLE II 300 grams of terpinolene were charged in a three-neck flask equipped with mercury seal stirrer, thermometer, and two reflux condensers, and heated to 330 F. Through one of the condensers 90 grams of sulfur were added portionwise over a period of one-half hour and at such a rate as to maintain the temperature of the reaction above 350 F. After the introduction of the sulfur the mixture .was heated for two and one-half hours at 330-350 F. and thereafter cooled, filtered and vacuum steam-stripped to 300 F. at 151-5 millimeters mercury. The small amount of free sulfur remaining in the reaction mixture was then removed by filtration and 100 grams of the sulfurized product were diluted with an equal volume of benzene and refluxed at 185-190 F., with violent agitation in the presence of a solution consisting of 222 grams of water, 111 grams of NazS.9HzO, and 33.3 grams of sodium hydroxide, for a period of four hours. The reaction mixture was then processed as in Example I and the resulting sulfurized terpinolene appeared as a light yellowish-brown oil which analyzed 28.7% sulfur.

EXAMPLE III 800 grams of terpinolene were heated to 260 F. on a pressure steam bath and 86 grams of sulfur were added in portions of 10 grams at a time for approximately one-half hour. During the introduction of the sulfur the temperature of the reaction was approximately 360 F. The reaction product was then cooled, filtered and vacuum steam-stripped to 300 F. at 15:5 millimeters mercury. The resulting sulfurized terpinene appeared as a yellow oil which analyzed 24.3% sulfur.

The proportions of these sulfurized terpenes added to a mineral lubricating oil may vary between 0.1 and 5.0% by weight, depending upon the particular base oil used and the type of engine and service involved. However, the range of proportions between 0.25 and 3.0% by weight have been found to be particularly effective in imparting excellent anti-oxidant or anti-corrosive and load-carrying properties to the mineral lubricating oil.

The compounds of the present invention may be used alone or in combination with other accepted improving agents, such as pour point depressors, oiliness agents, dispersing agents, detergents, blooming agents, color stabilizers, etc. Particularly when the lubricating oil is intended for service in Diesel engines or heavy duty gasoline engines, where the severe operating conditions are conducive to varnish and lacquer formation, it is desirable to add to the compounds of the invention an auxiliary additive functioning as a detergent and utilize the combination in the lubricating oil. Among the particular additives possessing detergent powers which may be used in combination with the sulfurized terpenes for operation in Diesel and heavy duty gasoline engines, are the phosphates, phosphites, metal soaps, phenols and metal phenolates. Experience has shown that the particular combination and range of proportions depends upon the type of engine and service and the type of base oil used. However, as a general rule, the range of proportions of the detergent additive, when used in .4 combination with'a sulfurized terpene, is preferably between 0.25 and 2.0% by weight.

As illustrative of the anti-oxidant or anti-corrosive properties of a mineral lubricating oil containing a small proportion of a sulfurized derivative of a terpene hydrocarbon, or the combination of a, sulfurized terpene hydrocarbon with a detergent additive, the results of the following empirical tests are presented:

A copper lead bearing specimen encased in a special non-wear bushing and rotatably mounted on a stainless steel shaft was immersed in a glass pot of the oil to be tested. The tested oil was heated to a controlled temperature of either 250 F. or 350 F. and continuously circulated between the bearing specimen and the shaft for 10 hours. The bearing specimen was weighed before the test and at the end of the 10 hour period the loss in weight was recorded in milligrams. The reference 011 used throughout this test was a solvent-refined dewaxed Mid- Continent lubricating oil distillate of SAE 30 grade. The results of two runs at both 250 F. and 350 F. are presented.

Bearing corrosion, copper-lead (10 hours) [Loss of Weight in Mga] Oil tested 250 F 350 F.

Reference nil 6, 7 148, 152 Reference oil plus 0.5% sulfurized terplnolcne. 0, 0 4, 1 Reference oil plus 0.5% barium (ll (polymer phenoiate) dlsuliido plus 1.0% sulfurized terpinolcnc 0, 1 0, 5 Reference oil plus 0.5% barium dimcthylaminomcthyl octylnhcnolate plus 1.0% sulfurized tcrninolene 0, 0 2, 2 Reference oil plus 0.5% barium amylthiomethyl nctylphenolate plus 1.0% sulfurized terplnoicne 2, 0 0, 0

Almen test Load, Oiltcsted pounds Reference oil 4. 6 Reference ol1+0.5% sulfurized terpinolene 10.0

A further illustration of the anti-corrosive properties of lubricating oils containing small proportions of a sulfurized terpene hydrocarbon is demonstrated by practical tests in a standard Plymouth engine equipped with copper-lead bearings. This test was carried out by running the engine for 24 hours at 3000 R. P. M. with three-quarter open throttle developing about 34 brake horsepower with the crankcase oil temperture maintained at 300 F. by means of an external heat exchanger with an external pump and with a water jacket temperature of 212 F. The hearings were disassembled, cleaned and weighed before and after each run and the results tabulated as the percentage weight loss difference between the experimental oil and the reference oil. The reference oil in this test was a solvent-refined, dewaxed Mid-Continent paraflln base lubricating oil distillate of SAE 30 grade and was compared to the same oil containing 0.5% sulfurized terpinolene. The results obtained showed 82% less bearing weight loss with the compounded oil than with the reference oil taken on an average of two test runs.

Another practical test was made on an automotive engine to confirm the superiority of the compounded oil of the present invention. This test was run in a standard Chevrolet engine operated on a block for 30 hours at an equivalent of 50 miles per hour, for 1500 miles, with a crankcase temperature of about 300 F., with a jacket temperature of 212 F., and a crankcase ventilation of one cubic foot per minute. At the completion of each run the engine was taken down, the pistons removed, and the varnish deposit dedetermined on the oil rings and the piston skirt. This was accomplished in each case by first washing with precipitation naphtha to remove re- I tained oil; then washing with acetone to remove the acetone-soluble portion of the varnish which was found to represent the bulk of the varnish deposit, then evaporating this acetone solution to dryness, extracting the residue with precipitation naphtha to remove the remaining traces of oil, again taking up in acetone solution and filtering to remove suspended carbon particles and impurities, and finally evaporating the acetone solution to dryness. The weight of the residue represents the combined deposit of the piston skirt and oil rings, and the results tabulated as the percentage improvement or the percentage reduction of the varnish deposit of the compounded oil as against the reference oil. The reference oil in this test was a solvent-refined, dewaxed Mid-Continent parafiln base lubricating oil distillate of SAE 30 grade and was compared with the same oil containing 0.5% sulfurized terpinolene. The results obtained showed an improvement of the compounded oil over the reference oil of 57.5% taken on an average of two test runs.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A method of lubricating an internal combustion engine provided with hard metal alloy bearings having the corrosive susceptibility of alloys of the class consisting of cadmium-silver and copper-lead alloys, which comprises applying to said bearings a lubricating oil normally corrosive to said bearings, and a small but suflicient quantity of a sulfurized monocyclic terpene hydrocarbon to inhibit the corrosion of said bearings by said mineral lubricating oil.

2. A method of lubricating an internal combustion engine provided with hard metal alloy bearings having the corrosive susceptibility of alloys of the class consisting of cadmium-silver and copper-lead alloys, which comprises applying to said bearings a lubricating oil normally corrosive to said bearings, and a small but sufficient quantity of sulfurized terpinolene to inhibit the corrosion of said bearings by said mineral lubricating oil.

3. Animproved lubricant adapted for use in internal combustion engines, which comprises a mineral lubricating oil having incorporated therein a small amount of a sulfurized monocyclic terpene hydrocarbon, suficient to impart corrosion inhibiting properties to the oil, and a small amount of an additive ingredient possessing detergent properties, sufficient to inhibit the lacquer and varnish-forming tendencies of the oil.

4. An improved lubricant adapted for use in internal combustion engines, which comprises a mineral lubricating oil having incorporated therein 0.25 to 3.0% by weight of a sulfurized monocyclic terpene hydrocarbon and 0.25 to 2.0% by weight of an additive ingredient possessing detergent properties.

EDWIN C. KNOWLES. FREDERIC C. McCOY. JOHN A. PATTERSON.

REFERENCES CITED The following references are of record in the file of this patent:

uNrrED STATES PATENTS OTHER REFERENCES Pg. 966 of Hackh's Chemical Dictionary (2nd Ed.) 1937. (CopyinDiv. 64.)

Pg. 484 of Richters Organic Chemistry, vo 11, Carbocyclic Series (1922). (Copy in Div. 64.) 

